Studies for next year will include: (A) Further investigation of the relationship of the subunit structure of physphorylase kinase to its catalytic activity. (B) Steady state kinetics of the reaction catalyzed by phosphorylase kinase. (C) Study of the mechanism of catalysis of glycogen phosphorylase with active site reagents. (D) Influence of peptides derived from the regulatory site of phosphorylase on phosphorylase structure and activity. The overall objective of this research is to increase our understanding of the mechanisms that control glycogen degradation in skeletal muscle. Detailed study of the various enzymes will be pursued to elucidate catalytic and regulatory mechanisms of glycogen phosphorylase, phosphorylase phosphatase, and phosphorylase kinase.